1. Field of the Invention
This invention relates in general to a variable equalizer, and more particularly, to a variable equalizer of the type which is used for compensation for the frequency characteristic variation in transmission lines in communication systems.
2. Description of the Prior Art
Although many kinds of variable equalizer circuits are well known in this field, there are few variable equalizers which are suitable for circuit integration and circuit simplification. The variable equalizer shown in FIG. 1, of which construction and operation will be described later, is one of conventional variable equalizers which are suitable for circuit integration.
The variable range over which the variable equalizer can operate effectively, is small since the variable equalizer is easily affected by the errors in circuit elements by the reason described later. Accordingly, in practical use, a plurality of variable equalizers have to be used in order to cover a wide compensation range. Therefore, it is important to construct variable equalizers as small and as economical as possible.